Method of forming necked-in can bodies

ABSTRACT

This disclosure relates to the necking-in of can bodies. It has been found that by inwardly curling an end portion of a can body prior to the performing of a necking-in operation thereon, the usual wrinkle formation resulting from a conventional necking-in operation is eliminated. The precurling may be performed by a rolling operation or by a die forming operation.

I United States Patent 1191 Hilgenbrink 1 Oct. 9, 1973 [5 METHOD OF FORMING NECKED-IN CAN 1,698,999 1/1929 Hothersall 72/370 BODIES 2,086,488 7/1937 Batie 72/82 [75] Inventor: John T. Hilgenbrink, Oak Lawn, Ill. FOREXGN PATENTS OR APPLICATIONS [73] Assignee: Continemal can p y, Inc. 488,628 7/1938 Great Britain 113/120 1-1 New York, NY.

Primary Examiner-Charles W. Lanham Filed: 1970 Assistant Examiner-Michael J. Keenan 21 pp No: 100 2 4 Att'omeyDi11er, BX'OWD, Ramik 8!. H011 [52] us. 01 113/120 R [57] ABSTRACT 511 1m. (:1. B2111 51/00 This disclosure relates I9 the neckmg-in of can bodies- 58 Field of Search 113/120 AA, 120 R, It has been found that y inwardly curling an end p ]13/120 5 120 H, 116 7 7 tion'of a can body prior to the performing of a necking-in operation thereon, the usual wrinkle formation 5 References Cited resulting from a conventional necking-in operation is UNITED STATES-PATENTS eliminated. The precurling may be performed by a rolling operation or bya die forming operation. 2,173,759 9/1939 McCloskey 113/120 S 1,948,437 2/1934 Bowers 113/120 S 7 Claims, 5 Drawing Figures METHOD OF FORMING NECKED-IN CAN BODIES This invention relates in general to new and useful improvements in the manufacture of can bodies, and more particularly relates to the necking-in of an end portion of a can body so as to conform the same for the reception of a smaller diameter end or cover.

BACKGROUND OF THE INVENTION It is well known to neck-in end portions of can bodies for the receipt of smaller diameter ends or covers. However, in such necking-in operations, minute wrinkles or pleats are formed and during the forming of the usual seam between the can body and the attached end, these small wrinkles or pleats result in'the formation of cracks and subsequent leaky cans.

A careful study of the undesirable formation of these wrinkles or pleats show that the instant the extreme end of the can body strikes the angled necking surface of the conventional necking die, these. wrinkles or pleats began to form.

It is to be noted that the undesirable wrinkles o pleats are particularly troublesome with respect to welded seam can bodies which has stress relief indents or notches on opposite sides of the welded side seam. However, the problem of the wrinkle or pleat formation is not restricted to welded side seam can bodies, the undesirable wrinkle or pleat formation also being found when the can body side seams are of the bonded type or of the lap and lock solder type and have been necked-in.

SUMMARY OF THE INVENTION- i can body end portion in advance of the presentation thereof to the conventional necking-in die greatly facilitates the necking-in operation providing for simplicity of tool design and advance speed of operation.

With the above and other objects in view that will hereinafter appear, the nature of the invention will, be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated'in the accompanying drawing:

IN THE DRAWING FIG. 1 is an elevational view with parts broken away and shown in section of a welded seam can body having stretch relieving notches formed in the extreme end edge thereof on opposite sides of the side seam.

FIG. 2 is a side elevational view showing the can body of FIG. I having the end portion thereof precurled in a roll forming operation.

FIG. 3 is an enlargement of a portion of FIG. 2 and shows specifically the details of the curling operation.

FIG. 4 is asectional view similar to FIG. 2 taken through a curling die showing the same being utilizing to precurl a can body.

FIG. 5 is a fragmentary sectional view through a customary type of necking-in die and shows the manner in which a precurled can body has the end portion thereof necked-in thereby.

Referring now to the drawing in detail, it will be seen that there is illustrated in FIG. I a typical can body which is to be necked-in in accordance with this invention, the can body being generally identified by the numeral 10. The can body 10 is of a cylindrical construction and is provided with a longitudinal side seam 11. The illustrated can body 10 has the side seam 11 thereof in the form of a welded side seam. However, in accordance with this invention, the side seam 11 could equally as well be of a bonded type construction or could be of a conventional lap and lock soldered construction. Particularly when the side seam 11 is a welded side seam, each end edge 12 of the can body 10 is provided with shallow stress relieving notches I3 closely adjacent to and on opposite sides of the side seam ll.

Reference is now made to FIG. 5 wherein there is illustrated a conventional type of necking die, which is generally identified by the numeral 14. The-necking die 14 includes a support 15 to which there is secured a die ring 16 which, in turn, is provided with a lead in or adapter ring 17. The necking die 14 also includes a die plug 18 which, in cooperation with the die 16 controls the sizing of the necked-in end portion of the can body. The plug 18 is mounted for limited radial shifting with respect to the support 15 and the die ring 16 by means of a fastener 20.

It will be readily apparent from FIG. 5 that when the can body 10 is necked-in utilizing the necking die 14, the main portion of the can body 10 remains of the original diameter and that the extreme end portion, which is necked-in, is also cylindrical, but of a reduced diameter. The necked-in end portion is identified by the numeral 21 and is connected to the remainder of the can body 10 by a generally cylindrical intermediate portion 22. i

When the can body 10 is necked in directly within the necking die 14, axially extending wrinkles are formed circumferentially about the necked-in end portion 21. This is particularly true when the end edge 12 of the can body is provided with the radius notches 13. Wrinkles or pleats form in alignment with the radius notches 13. Furthermore, ithas been found that with wrinkles or pleats either before or during the seaming of an end to the can body 10, cracks occur along the wrinkles or pleats which result in leaks in the finished can.

In accordance with this invention, it has been found that by precurling the end portion of the can body radially inwardly, as is illustrated on a large scale in FIG. 3, formation of the pleats or wrinkles and the resultant cracks is substantially eliminated. The precurled end portion of the can'body 10 is identified by the numeral 23 and the precurling occurs about a relatively small radius, but is limited to a radial inwardly curling of the end portion of the can body to a diameter no less than the diameter of the necked-in end portion 21.

As is illustrated in FIG. 2 and 3, the curl 23 may be formed by placing the can body 10 on a suitable mandrel 24 and progressively subjecting the end of the can body 10 to a rolling action by means of one or more rollers 25. The mandrel 24, in cooperation with the roller 25, provides for the desired curl configuration.

Referring now to FIG. 4, it will be seen that there is illustrated alternative apparatus for forming the curl 23. This apparatus is in the form of a die assembly which is generally identified by the numeral 26. The die assembly 26 includes a support 27 to which there is secured in any conventional manner an outer die ring 28. The die ring 28 is of an internal configuration which includes a lead-in angle 30, a guide portion 31, which corresponds to the diameter of the can body 10, and a curling radius 32. The die assembly 26 also includes a die center plug 33 which is seated in the die ring 28 and is secured to the support 27 by means of a fastener 34. The die center plug 33 projects axially into transverse alignment with the die radius 32 so as to limit the radial inward extent of the curl 23.

It is to be understood by limiting the inward curling of the end portion of the can body to a diameter no less than the diameter of the necked-in end portion 21, the precurled can body may be readily necked-in utilizing the die 14 in the conventional manner. However, because the extreme end 12 of the can body 10 is already substantially at the final diameter of the neckedin end portion 21, when the extreme end 12 of the can body 10 strikes the necking die, there is no immediate formation of wrinkles or pleats as is customary. The preforming of the curl 23 in no way interferes with the necking-in operation and, in fact, facilitates the flow of metal as is required in the necking-in operation.

It is to be understood that the precurling of the can body may be readily accomplished in any desired manner which does not require an abrupt overstressing of the end edge of the can body and which will provide for a uniform curling of the end portion of the can body.

Although only several preferred die assemblies for forming the necked-in end on the can body have been specifically illustrated and described, and the invention, in the description thereof has been limited to a can body as the cylindrical member, it is to be understood that the invention is not so limited, and minor modifications may be made in the invention without departing from the spirit and scope of the invention, as defined by the appended claims.

I claim:

1. A method of necking-in an end portion of a can body having a side seam in a manner to eliminate wrinkling particularly adjacent the side seam, said method comprising the steps of first inwardly curling the can body end portion utilizing a curling device, and then applying a necking-in die assembly to the inwardly curled end portion only in an axial direction and further changing the configuration of said end portion from an inwardly curled configuration to a cylindrical configuration of reduced diameter as compared to the original diameter of the can body and a conical intermediate configuration joining the reduced diameter cylindrical configuration to the remainder of the can body.

2. The method of claim 1 wherein the inwardly curling of said end portion is restricted to a diameter at least as great as the diameter of said reduced diameter cylindrical configuration.

3. A method of necking-in an end portion of a can body having a side seam in a manner to eliminate wrinkling particularly adjacent theside seam, said method comprising the steps of first inwardly curling the can body end portion, and then applying a necking-in die assembly to the inwardly curled end portion and further changing the configuration of said end portion from an inwardly curled configuration to a cylindrical configuration of reduced diameter as compared to the original diameter of the can body and a conical intermediate configuration joining the reduced diameter cylindrical configuration to the remainder of the can body, together with the formation of stress relieving notches in the extreme end edge of said end portion in positions to be disposed on opposite sides of and closely adjacent said side seam, said notches being formed prior to said curling step.

4. The method of claim 3 wherein the inwardly curling of said end portion is restricted to a diameter at least as great as the diameter of said reduced diameter cylindrical configuration.

5. The method of claim 4 wherein said curling operation is accomplished by a rolling operation.

6. The method of claim 4 wherein said curling operation is accomplished by a die forming operation.

7. The method of claim 1 wherein the conical intermediate configuration is formed to be a straight line conical configuration. 

1. A method of necking-in an end portion of a can body having a side seam in a manner to eliminate wrinkling particularly adjacent the side seam, said method comprising the steps of first inwardly curling the can body end portion utilizing a curling device, and then applying a necking-in die assembly to the inwardly curled end portion only in an axial direction and further changing the configuration of said end portion from an inwardly curled configuration to a cylindrical configuration of reduced diameter as compared to the original diameter of the can body and a conical intermediate configuration joining the reduced diameter cylindrical configuration to the remainder of the can body.
 2. The method of claim 1 wherein the inwardly curling of said end portion is restricted to a diameter at least as great as the diameter of said reduced diameter cylindrical configuration.
 3. A method of necking-in an end portion of a can body having a side seam in a manner to eliminate wrinkling particularly adjacent the side seam, said method comprising the steps of first inwardly curling the can body end portion, and then applying a necking-in die assembly to the inwardly curled end portion and further changing the configuration of said end portion from an inwardly curled configuration to a cylindrical configuration of reduced diameter as compared to the original diameter of the can body and a conical intermediate configuration joining the reduced diameter cylindrical configuration to the remainder of the can body, together with the formation of stress relieving notches in the extreme end edge of said end portion in positions to be disposed on opposite sides of and closely adjacent said side seam, said notches being formed prior to said curling step.
 4. The method of claim 3 wherein the inwardly curling of said end portion is restricted to a diameter at least as great as the diameter of said reduced diameter cylindrical configuration.
 5. The method of claim 4 wherein said curling operation is accomplished by a rolling operation.
 6. The method of claim 4 wherein said curling operation is accomplished by a die forming operation.
 7. The method Of claim 1 wherein the conical intermediate configuration is formed to be a straight line conical configuration. 